A method for forming non-planar capacitors of desired dimensions is disclosed. The method is based on providing a three-dimensional structure of a first material over a substrate, enclosing the structure with a second material that is sufficiently etch-selective with respect to the first material, and then performing a wet etch to remove most of the first material but not the second material, thus forming a cavity within the second material. Shape and dimensions of the cavity are comparable to those desired for the final non-planar capacitor. At least one electrode of a capacitor may then be formed within the cavity. Using the etch selectivity of the first and second materials advantageously allows applying wet etch techniques for forming high aspect ratio openings in fabricating non-planar capacitors, which is easier and more reliable than relying on dry etch techniques.